[Gnash] resizing a swf - change the aspect ratio

[hacky]

hi guys,
I want to display a flash (swf) file e.g. 1024x576 on a 4:3 monitor full
screen. I'm using gnash (gtk) with fluxbox. "gnash --fullscreen (...)"
works fine to the point that I want to stretch the file also vertically.
I want to get rid of the white borders at the top and at the bottom... I
noticed that the aspect ratio is fixed and I found no option in the
manual. Is it possible to have influence on the aspect ratio?

Best,
Grischa